Membrane Science and Separation Technology Division, CSIR-Central Salt and Marine Chemicals Research Institute (CSIR-CSMCRI), Gijubhai Badheka Marg, Bhavnagar, Gujarat, 364002, India.
Central Institute of Petrochemicals Engineering and Technology, Ernakulam, 683501, Kerala, India.
Environ Sci Pollut Res Int. 2024 Mar;31(14):21157-21171. doi: 10.1007/s11356-024-32520-w. Epub 2024 Feb 22.
This study investigates the impact of solvent post-treatment on polyamide-based thin film composite (TFC) membranes, specifically examining the effect on commercial nanofiltration (NF) and reverse osmosis (RO) membranes. NaSO rejection and increase in pure water permeance (PWP) were considered as the output parameters. The disparity in Hansen solubility parameters (HSP) between the post-treatment solution and the polyamide layer of the TFC membrane, denoted by Ra, is well adapted to understand the enhancement in water permeance through the membranes upon treatment. Aqueous solutions of dimethylformamide with a Ra value of 4, acetonitrile with a Ra value of 8.3, and ethanol with a Ra value of 12.7 were used as the post-treatment solutions. Our experimental design, based on the Box-Behnken design of Response Surface Methodology, incorporates variables such as the concentration of the solvent in the solution (% v/v), Ra value, and treatment time (s). Our findings demonstrate that the effect of post-treatment on the TFC membranes is not governed by the Ra value. Notably, while the post-treatment with the aqueous solution of acetonitrile, 80% v/v for 30 s, had considerable effects on NF membranes (124.5% enhancement in PWP; reduction of 3.5% in NaSO rejection), its impact on RO membranes was negligible. Several factors explain this discrepancy, including the limitations of the HSP model for composite polymers, the inaccuracy of the PWP or salt rejection as a swelling indicator, variations in the HSP values of the polyamide layers for different membranes, and possible modifications in the interface between the support membrane and the polyamide layer. In summary, our study provides insights into the complex interactions between solvents and composite membranes, indicating that HSP alone is not a decisive factor in predicting post-treatment effects on polyamide-based TFC membranes.
这项研究调查了溶剂后处理对聚酰胺基薄膜复合（TFC）膜的影响，特别考察了其对商业纳滤（NF）和反渗透（RO）膜的影响。纳滤（NF）和反渗透（RO）膜的截留率（NaSO）和纯水透过率（PWP）的增加被视为输出参数。后处理溶液与 TFC 膜的聚酰胺层之间的 Hansen 溶解度参数（HSP）差异（用 Ra 表示），很好地适应了通过处理增强膜的水透过率。用作后处理溶液的是具有 Ra 值为 4 的二甲基甲酰胺的水溶液、Ra 值为 8.3 的乙腈的水溶液和 Ra 值为 12.7 的乙醇的水溶液。我们的实验设计基于响应面法的 Box-Behnken 设计，包含了溶液中溶剂的浓度（% v/v）、Ra 值和处理时间（s）等变量。我们的研究结果表明，后处理对 TFC 膜的影响不受 Ra 值的控制。值得注意的是，尽管用 80%v/v 的乙腈水溶液处理 30s 对 NF 膜有很大的影响（PWP 提高了 124.5%；NaSO 截留率降低了 3.5%），但其对 RO 膜的影响可以忽略不计。有几个因素可以解释这种差异，包括复合聚合物的 HSP 模型的局限性、PWP 或盐截留率作为溶胀指标的不准确性、不同膜的聚酰胺层的 HSP 值的变化以及支撑膜和聚酰胺层之间的界面的可能改性。总之，我们的研究深入了解了溶剂和复合膜之间的复杂相互作用，表明 HSP 本身并不是预测聚酰胺基 TFC 膜后处理效果的决定性因素。
